Tips for calling 911 with a cell phone - Peek under hood

[Joseph]

I am a software developer working with online maps and location technology. Earlier this year I became interested in what happens when someone with a cell phone calls 911. In particular I wanted to know the details of how the 911 dispatcher learns the *location* of the caller. What kind of digital magic happens behind the scenes?

Much of what I learned came from reviewing documents on the FCC’s website. On one hand I learned that the FCC requires a wireless carrier handling a 911 call to produce coordinates for the caller’s location. Sounds good, right? On the other hand I learned that many carriers have exempted themselves from this requirement over large portions of the area they serve. I also learned that the coordinate accuracy most of us easily get on our smartphones (or handheld GPS) is often 10 times more accurate - or more - than the coordinates produced by the wireless carrier handling a 911 call.

Recently I finished a report that shares what I learned. That report consists of:
1. A list of tips for calling 911 with a cell phone.
2. Background information so you understand the big picture.
3. Detailed information to support each tip.
For those wishing to dig into the source material for themselves, the report includes links to various documents on the FCC website.

I posted a copy of this report on my server at
https://mappingsupport.com/p/sar/call-9 ... -phone.pdf

Here are the tips. I am happy to answer questions.

--- Tip #1 ---
If you need to call 911 and your cell phone shows ‘no service’, then you should call 911 anyway and let it ring 45-60 seconds before hanging up.

--- Tip #2 ---
You should give the 911 dispatcher your location by providing (1) a street address, or (2) a verbal description the dispatcher understands, or (3) your latitude longitude coordinates expressed as decimal degrees.

--- Tip #3 ---
FindMeSAR is a browser app that was developed as a public service specifically to provide an easy and ‘no cost’ way for anyone with a smartphone to display their coordinates and accuracy value while their phone is either online or offline. This is not a commercial product of any kind. It is a volunteer project just to try and help people when they need help.

--- Tip #4 ---
When you call 911 with a cell phone the wireless carrier handling the call might not produce *any* coordinates for your location.

--- Tip #5 ---
Even if the wireless carrier handling your 911 call does produce coordinates for your location, the coordinates you can obtain from your smartphone are either (1) more accurate or (2) a lot more accurate than the coordinates produced by the wireless carrier.

--- Tip #6 ---
If (1) your phone is not within range of a cell tower and (2) your phone does not have a current copy of the satellite ‘assistance’ data, then it will take 15 to 20 minutes before your phone will produce coordinates for your location.

--- Tip #7 ---
No one is monitoring the wireless carriers to see whether or not they are in compliance with the standards and requirements that the FCC has adopted regarding wireless calls to 911 and coordinate data for the caller’s location.

--- Tip #8 ---
If you have an android phone then to get the most accurate coordinates set the location mode (or method) to “GPS only”.

--- Tip #9 ---
If you have an Android phone then there is a free and easy way to find out if your phone can produce more accurate coordinates by using data from both the USA satellites (GPS) and the Russian satellites (GLONASS).

--- Tip #10 ---
Phones that have no service plan at all can still (1) call 911 and (2) run an app that displays coordinates and accuracy on the phone’s screen.

--- Tip #11 ---
If at all possible, make a voice call to 911 instead of texting.

--- Tip #12 ---
If you do text to 911, then the dispatcher is most likely not going to have *any* location data for you unless you include it in your text.

--- Tip #13 ---
After you contact 911 take steps to make your phone’s battery last as long as possible.

Joseph

[balzaccom]

Very good info. I generally don't take a phone with me on my backpacking trips, but the one time I did, I was surprised by the fact that I sometimes had cellphone coverage, and that my GPS worked just fine...

[maverick]

Thnaks for the info.

[zacjust32]

Very interesting and good to know how it works. I've heard lots of 911 calls on tv and the internet and it's amazing how little comprehension people have when adrenaline is pumping and they're under distress. I'd like to ask you or any SAR here what should be included in a 911 call.

I'm thinking:

1. Location
2. Name
3. Situation
4. Other people if any
5. Resouces
6. ????

[Joseph]

@zacjust32, also give your phone number so the dispatcher can call you back if the call is dropped.
===============================

Here is a followup idea to help find people that have called 911 and are not able to give a street address or adequately describe their location.

As explained in the report I posted, when someone with a cell phone calls 911 the wireless carrier is supposed to make reasonably good coordinates available to the dispatcher. Often times that system works fine. But also many times this system does not work well and either the wireless carrier never produces “phase 2” coordinates or do so but the accuracy of the coordinates is terrible.

There are 6,000+ 911 call centers in the USA. These are known as PSAPs (Public Safety Answering Point. The problem of wireless carriers not providing accurate coordinates for wireless callers is going to vary from one PSAP to the next.

Now here is the idea. When a 911 dispatcher has a problem getting an accurate location for a wireless caller, the dispatcher can ask the caller to:
1. Browse to findmesar.com
2. Tap the "Next format" button until the yellow screen appears. This screen shows the caller's location in decimal degrees which is the same format the wireless carriers use to send location data to 911 call centers.
3. Wait a few seconds for the accuracy to get to 30 meters or smaller.
4. Tap "Stop"
5. Read off the coordinates, accuracy, timestamp and (optionally) elevation.

No, this will not work in every case. FindMeSAR does not work on flip phones. And the first time someone tries to use this app their browser has to be online. Unless the phone is on wi-fi, this means the phone has to have a data plan.

Yes, FindMeSAR will work in many cases and the person who called 911 for help will be able to very quickly read accurate coordinates to the dispatcher. Here is a short report from a SAR team in New Mexico that used FindMeSAR to locate lost hikers. The story seems to indicate that “phase 2” coordinates from the wireless carrier were also available but they were not accurate. http://atalayasar.org/

Also FindMeSAR has been reviewed and added to the APCO app page at http://appcomm.org/. APCO is an international organization for public safety communication professionals.

If you know someone who works in public safety (dispatcher, police, fire fighter, SAR, etc) please consider asking them to take a look at this idea of your local PSAP using FindMeSAR as a backup plan to help locate wireless callers.

Finally, I will point out again that FindMeSAR is not any kind of commercial product. Over the years I have traveled in the backcountry a fair bit on foot, skis and horseback. Fortunately I have never needed to call for help but I know people that have not been as lucky. This volunteer project is part of my way to 'pay it forward' and also show appreciation for all those involved in SAR and other emergency response.

Joseph

[The Other Tom]

Joseph
Thank you for this interesting information and for your work in this area. Question:
Would it be possible to make FindMeSar an app instead of having to open a browser and then navigating to a web site ? I'm not trying to be critical of your efforts, which I very much appreciate, but maybe it would be easier if it was an app.

[Joseph]

Joseph
Thank you for this interesting information and for your work in this area. Question:
Would it be possible to make FindMeSar an app instead of having to open a browser and then navigating to a web site ? I'm not trying to be critical of your efforts, which I very much appreciate, but maybe it would be easier if it was an app.

Yes and no.

Yes, someone who was knowledgable about developing native apps could certainly produce a native app that works just like FindMeSAR.

No, I do not know how to do that.

FindMeSAR is a browser app and is written mostly in javascript. By contrast, native apps are developed in different programming languages. There is one language for iOS native apps and a different language for Android native apps.

But with all that said, did you notice that FindMeSAR includes an icon that you can save on your screen? Once you do that then you can launch this browser app exactly like you launch native apps - by tapping its icon.

[The Other Tom]

Thanks for the follow up(and education about how software works). I had missed the icon. That's a good idea and I'm glad you pointed it out to me.